Fall is the time to take action against cheatgrass

If you live in northern Larimer County, you likely have experienced the aggravations of cheatgrass: socks full of prickly seeds; dogs irritated by seeds in their ears and paws; and patches of your pasture or hayfield taken over by a grass that dries up early in the season, producing minimal forage. Where did this irritating plant come from? And more importantly, what can be done to eliminate it?

By Ellen Nelson
Larimer County Weed District

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Cheatgrass has been “cheating” landowners for years. It originally arrived from Europe as a contaminant in grain and other seed in the late 1800’s. It was also used as packing material for settlers moving west. It spread easily in the coats of animals, and along railways and roads. Cheatgrass is a winter annual, it germinates and begins growing in the fall, and over-winters as a seedling, “cheating” with this “head start” the following spring. The head start coupled with a very rapid growth rate very early in the spring allows it to outcompete native vegetation for water and nutrients. Cheatgrass readily establishes in disturbed areas. Cheatgrass produces seeds and goes dormant very early, leaving an abundance of very fine fuel leading to increased fire frequency and size. This cheatgrass-initiated fire cycle makes it difficult to re-establish native vegetation. A healthy stand of cheatgrass produces as many as 25,000 seeds per square yard. A seed bank of this magnitude simply overwhelms native perennials.

Fortunately, there are some actions you can take to combat this invasive weed. Some herbicides are effective when used at the proper time of year, and some perennial grasses have been shown to compete well with cheatgrass. The ideal time to treat cheatgrass with herbicide is in the fall, when it germinates and begins to grow.

The Larimer County Weed District recommends the herbicides Plateau or Panoramic to treat cheatgrass, applied at 4 to 6 ounces per acre in the fall. It may be advantageous to remove the previous year’s dried up old growth to allow the herbicide to contact the cheatgrass seedlings. If you are familiar with some of the County’s Open Space areas, you may be aware of some local success stories. The Weed District treated 160 acres at Devil’s Backbone Open Space in October of 2010 with 6 oz per acre of Plateau. Happily the timing of that treatment, and the luxurious amounts of precipitation in May and June of 2011 resulted in a wonderful resurgence of the native grasses. The Weed District treated approximately 500 acres of cheatgrass in 2010, including areas at Eagle’s Nest and Red Mountain Open Spaces. If you are familiar with these natural areas, note if you can see a difference in the vegetation in these areas.

Current research on several types of fungus may provide an alternative way to combat this aggressive weed in the future. One fungus, the Black Fingers of Death, originating in Eurasia, attacks newly forming cheat grass seeds and may markedly decrease viable seed production, allowing native grasses to compete for nutrients and water. Research currently underway in Utah may lead to a bio-control option in the future.

Sometimes, simply eliminating the first fall flush of cheatgrass is all that is needed to release the native perennial grasses for a resurgence of native vegetation. Native grasses that reassert themselves when cheatgrass is removed are western wheat, blue grama, sideoats grama, needleandthread grass, green needlegrass and many more. In areas with large monocultures of cheatgrass over a long period of time, it may be wise to reseed with perennial grasses rather than leave an open invitation for other undesirable weedy species to move in. There are many perennial grasses that compete well with cheatgrass.

When reseeding native grasses, consider the species listed above. There is an ongoing debate in the natural resources community about reseeding with non-native grasses, especially if they can out-compete cheatgrass more effectively than native grasses. Several cultivars of crested wheatgrass have been shown to compete very well with cheatgrass, and even though this is not a native grass, it provides more forage, less fire danger and an opportunity for vastly improved range and pasture than a monoculture of cheatgrass. For recommended seed mixes, especially if reseeding after wildfire, contact the Natural Resources Conservation Service Fort Collins office at 2150 Centre Ave., Building A, Suite 116, 970-295-5655.

For more information on weeds, weed identification, pasture management, reseeding, herbicide recommendations and free site visits please contact the Larimer County Weed District 2649 E Mulberry, Suite 6, or call 970-498-5768.